Odour Mitigation Measures SE - scambs.gov.uk · Former Bayer Crop Science Site Initial Review of...

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Vertase F.L.I. Limited 3000 Aviator Way Manchester Business Park Manchester M22 5TG Tel +44 (0) 161 437 2708 Fax +44 (0) 161 437 6300 Email [email protected] www.vertasefli.co.uk Review of Odour Mitigation and Odour Management Measures Former Bayer Crop Science Site Hauxton Cambridgeshire Environmental Permit Ref: ERP/QP3293FY 2 nd June 2010 Author: M.J. Allsobrook M.Sc. B.Sc. Project Manager On behalf of: Harrow Estates Plc

Transcript of Odour Mitigation Measures SE - scambs.gov.uk · Former Bayer Crop Science Site Initial Review of...

Page 1: Odour Mitigation Measures SE - scambs.gov.uk · Former Bayer Crop Science Site Initial Review of Odour Mitigation and Odour Management Measures. May 2010 1 1.0 Introduction 1.1. General

Vertase F.L.I. Limited3000 Aviator WayManchester Business ParkManchester M22 5TG

Tel +44 (0) 161 437 2708Fax +44 (0) 161 437 6300

Email [email protected]

Review of Odour Mitigation and Odour Management Measures

Former Bayer Crop Science SiteHauxtonCambridgeshire

Environmental Permit Ref: ERP/QP3293FY

2nd June 2010

Author:

M.J. Allsobrook M.Sc. B.Sc.Project Manager

On behalf of:

Harrow Estates Plc

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REPORT TITLE: Review of Odour Mitigation and Odour Management Measures REPORT NUMBER: 907BRI-MA-12.3-020610/001 CLIENT NAME: Harrow Estates

This report has been prepared by Vertase F.L.I. Limited with all reasonable skill, care and diligence and is based on the resources devoted to it by agreement with the client. The report is confidential and for the sole use of the client and for the specific scheme as referred to herein. The copyright of the report is held by Vertase F.L.I. Limited. Copies may be passed to third parties only with the express written permission of Vertase F.L.I. Limited and then no professional liability or warranty will be extended to such parties without the express written confirmation of Vertase F.L.I. Limited. The report is only valid when used in its entirety. The findings and opinions contained in this report are based on information from a variety of sources which Vertase F.L.I. Limited believes to be reliable. Whilst this information has been accepted in good faith Vertase F.L.I. Limited cannot guarantee its reliability or authenticity. All potential contamination, constraints or liabilities associated with the site may not necessarily have been revealed. The potential exists for variations in soil and groundwater conditions, including contaminant concentrations, between and beyond the specific locations investigated. No liability can be accepted for such variations.

Author Signed Date

M Allsobrook

01/06/2010

Project Manager Signed Date

M Allsobrook

01/06/2010

QA Approved Signed Date

S Edgar

01/06/2010

Issue:1 Final Revision

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CONTENTS

1.0 Introduction ........................................................................................................................... 1

1.1. General.......................................................................................................................... 1

1.2. The Site ......................................................................................................................... 1

1.3. Remediation Brief and Philosophy ................................................................................ 2

2.0 2.0 Review of Contamination ......................................................................................... 3

2.1. Soil and water contamination ........................................................................................ 3

2.2. Compounds in Air (VOC’s) ............................................................................................ 3

2.3. Odours........................................................................................................................... 3

3.0 Site Monitoring ................................................................................................................ 5

3.1. Instantaneous Offsite Monitoring................................................................................... 5

3.2. Offsite Monitoring (28Day Passive)............................................................................... 5

3.3. PID Monitoring............................................................................................................... 6

3.4. On site 24 Hour Pumped Samples................................................................................ 6

3.5. Qualitative Odour Profiling ............................................................................................ 7

4.0 Scope of Remediation Works......................................................................................... 8

5.0 Current Mitigation Measures........................................................................................ 10

6.0 Mitigation Measures for Excavation Phases .............................................................. 15

7.0 Mitigation Measures for Turning windrows ................................................................ 18

8.0 Summary........................................................................................................................ 22

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1.0 Introduction

1.1. General

The purpose of this report is to produce a summary of odour control measures at the former

Bayer Cropscience Site currently employed to date during the first phase (largely excavation

and processing) and to review these measures and those initially proposed in the Environmental

Permit for the remaining phase of work (largely ex-situ soil treatment and restoration). This will

provide basis for the ongoing assessment review of procedures for odour management at the

site.

The mitigation measures within this report will be supplemental to the approved Deployment of

Vertase FLI’s Environmental Permit Ref: ERP/QP3293FY for the remediation works at the

former Bayer CropScience site Hauxton, Environmental Permitting Regulations 2007.

1.2. The Site

The site is the former Bayer Crop Science site, Cambridge Road, Hauxton, Cambridge. The site

was used for the storage and production of agrichemicals from the 1940’s through to ceasing

production in 2004. The site was used primarily for the synthesis, formulation, packaging and

storage of agrichemicals (both herbicides and pesticides). It is this former historical use that has

led to the contamination legacy of soil and groundwater at the site.

There is also a Waste Water Treatment Plant (WWTP) and other agricultural land which is part

of the former land holding of Bayer Crop Science and is part of that controlled by Harrow

Estates. The WWTP will be utilised to assist in the treatment of recovered groundwater and will

be improved to undertake this task and then maintained for the duration of the remediation. This

area of the site will not be subject to remediation as part of this phase of works but will be

remediated as a separate phase of work under a separate contract and separate Remediation

Method Statement in the future.

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1.3. Remediation Brief and Philosophy

The philosophy for this remediation project is set out in detail in the agreed Remediation Method

Statement. The remediation of the site has been developed from knowledge of the site gained

from historical site investigations, Atkins Preliminary Conceptual Model Report August 2006

(interpretative report defining the current and correct understanding of the geological and

environmental conditions) and subsequent sampling and analysis defining the extent of

contamination following further investigation. This information has allowed the conceptual site

model and pollutant linkages to be developed to form the remediation methodology. Whilst the

remediation work itself is complex and varied, the philosophy is simple and defines the proposed

remedial action required. This philosophy has been designed with the brief in mind. This brief

can be defined as “a remediation to address all pollutant linkages and ensure that following

remediation and re-development no unacceptable risks will remain associated with the treated

area of the site by applying the best available techniques not entailing excessive costs

(BATNEEC)”.

The philosophy behind the remediation is to remove all uncertainty relating to soils and

groundwater within the site area by the excavation, characterisation and treatment. All

pathways between the identified sources and receptors will be removed and the contaminant

mass within soils reduced as far as the practical limits of cost effective technology permit. The

Remediation Method Statement sets out how this philosophy or strategy will be achieved

practically on site and validated with confirmative post remediation risk assessment.

These remediation works are also required to satisfy the regulators that adequate remediation

works have been completed to satisfy their requirements under Part IIa of the Environmental

Protection Act 1990.

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2.0 Review of Contamination

The various site investigations carried before and after the decommissioning of the site identified

a number of areas of contamination within the soils and groundwater.

2.1. Soil and water contamination

The contaminants in the made ground, sands and gravel, marl, clay and groundwater are

solvents, chlorinated solvents, general hydrocarbons, phenolics and also the products and

intermediates ad derivatives of the pesticides and herbicides manufactured at the facility. Many

of these contaminants are solvents and organic chemicals found on many other contaminated

sites and indeed used in everyday products such as petrol.

2.2. Compounds in Air (VOC’s)

To date the most abundant of the contaminants recorded via long term passive VOC monitoring

are 1,2,4-Trimethylbenzene, Naphthalene, Benzene, Toluene, Ethyl benzene, and Xylene all of

which can produce distinctive odours and can be associated with general industry ad also from

traffic fume. These were also found pre-remediation activity. Phenol and Tetrachloroethylene

have also been identified again which can have distinctive odours and a are likely associated

with the remediation works or contaminated soils and waters at the site. General straight chain

alkanes and alkenes have also been identified which may be attributable to many different

sources. ,In addition some of the compounds used to aid in the control of odours (the control of

odours being distinct in some cases from the control of VOC’s) have also been detected.

2.3. Odours

There are also some compounds such as chlorinated phenols or even some of the chemicals

manufactured previously at the site that may be perceived as an odour before they are

detectable even at the lowest of detection limits and whilst not detected during monitoring they

may still be contributing to odours. Because these can be perceived does not mean that they

are present in concentrations that may be damaging to health. For these reasons we review

and address the two issues of odour control and VOC control as two separate but linked issues.

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Both issues requiring careful monitoring and management along with appropriate control

measures.

.

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3.0 Site Monitoring

There are five main elements to the air monitoring regime at the former Bayer Cropscience Site.

These are aimed at long term monitoring to monitor off site exposure, short term monitoring to

protect off site exposure and on site exposure, instant monitoring to provide early warning

personnel monitoring to monitor on site exposure and qualitative odour monitoring to build an

odour profile on and around the site.

3.1. Instantaneous Offsite Monitoring

The Vertase FLI Environmental Engineers monitor for odours and VOC’s using a Photo

ionisation Detector (PID) around the entire site boundary as a minimum twice daily during the

site working hours. All odours detected olfactorily are rated, commented upon and recorded on

the appropriate monitoring form. If odours are detected off site on site discussions and actions

are undertaken on site to reduce the impact of VOC/odours off site, these actions are logged on

the environmental monitoring forms.

In addition independent boundary odour assessment is undertaken on a daily basis by Atkins’

Resident Engineer. All site odours detected off site are reported immediately to the Vertase FLI

site team, with the deployment of further mitigation measures where required and where

practicable.

Visiting management, clients representatives and regulators also undertake boundary odour

assessment in tandem with the site engineers to both ensure that permanent site staff are not

becoming desensitised to the site odours , that all odour assessors are detecting odours at the

same locations, at the same concentration and reporting the same severity scale as well as

providing additional supplementary information and a “quality control” type check.

3.2. Offsite Monitoring (28Day Passive)

There were initially 9 agreed monitoring locations off site for the 28-day passive monitoring

devices. This has now been increased to eleven. The eleven 28-day air samplers are located

outside the site boundary to monitor VOC levels between the site and potential receptors.

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These tubes are removed and analysed on a 28 day basis providing a 28 day average for

comparison to threshold concentrations and for consideration by the regulators and the site

team. This regime was commenced before the start of the contract works to provide baseline

data and will continue beyond completion.

Where possible the results will be compared to UK air quality standards and World Health

Organisations recommendations by the independent governmental organisation the Health

Protection Agency, to ascertain whether there is a potential for a toxicological hazard to people

off site. The VOC’s identified on the sampling media to date are a mixture of traffic exhaust

related compounds, site related compounds, odour controlling compound, and other general

background compounds. Results of this monitoring are also discussed in detail with the Health

Protection Agency.

3.3. PID Monitoring

A MiniRAE PID is used for the monitoring of peak concentrations on site and to provide a real

time assessment of any gross VOC emission from site. These are recorded both on site at the

source of the emission and off site beyond the boundary at eight monitoring locations. This

helps to identify peak emissions and enable real time decisions on site with regard to VOC

management.

3.4. On site 24 Hour Pumped Samples

On site 24 hour samples are also taken to establish the emission from site on a pumped sample

basis. This will be correlated with both the PID data, observations and the 28 day tubes to

attempt to better understand the relationships. It also allows us to monitor the moving 28-day

average but with a quicker turnaround due to the shorter exposure time for the tubes. These

will also be used to assess exposure for on site personnel.

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3.5. Qualitative Odour Profiling

Observations are made on and around the site to establish the nature, extent and level of

odours and where possible relate this to activities and VOC levels. An established protocol and

guidance for this is in place.

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4.0 Scope of Remediation Works

The Scope of Works at the site involves several stages each with their own challenges and

complexities. The following is a generalisation of the main individual remediation tasks with an

estimation of percentage complete to date. Based on observations this table also gives an

indication of the phases in which the worst of the odours are likely to occur and demonstrates

that the majority of the high odour risk work is underway with remaining activities yet to

commence unlikely to increase the scale of emissions be they VOC or odour.

Task % complete Notes

Excavation of made

ground

15% Concrete and other hard materials require excavation to

expose the contaminated materials below. This material is

a low (sometimes moderate) odour contributor, the

materials below this level will potentially be greater odour

source.

Excavation of

deeper materials

15% A greater volume of contaminated material is present

beneath the madeground where particularly odours

contamination is present, this material requires excavation

and treatment on site. This activity is a significant odour

contributor as material is exposed to the air. Prior to

excavation the material had remained in the ground

contaminated for up to 70 years. Much of this material is

cohesive and requires processing with processing

buckets. The excavation phase is likely to have the

greatest potential for odour and VOC release.

Processing of

materials

15% Contaminated soils are processed in the processing area

to remove unwanted materials and enable treatment of the

contaminated materials. This activity is a moderate odour

contributor as material is exposed to the air.

Treatment of soils 2% Soils are prepared into windrows for both drying and

treatment. The majority of soils are clays or chalky clays

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requiring drying and processing before treatment. Material

requires continued turning to permit drying and allow

aeration/oxygen supply to facilitate the remediation. This

activity is a low to moderate odour contributor depending

on the level of contamination within a particular bed as the

majority of the odours have dissipated by this stage, if

required materials can be quickly covered to reduce odour

generation.

Replacement of

treated material

0% Materials are replaced as targets are met. It is important

to note that the targets are risk assessed and the material

may still have some odour albeit significantly reduced

following treatment. This activity is a low to non odour

contributor.

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5.0 Current Mitigation Measures

The initial deployment form proposed a number of control measures which were reviewed once

work commenced and supplemented with further measures where required. The table below

outlines steps taken during each part of the works to mitigate odours and shows the likely level

of soil/water contamination present for each activity indicating its potential (unmitigated) for VOC

release. Remembering of course that high VOC and Odour may not always be inextricably

linked. In addition to the practical measures described below we have also tried to work closely

with the SCDC and the EA regarding the issues discussing the site and keeping them informed

of particular problem areas. In addition we have attempted to keep the local residents abreast

of activities with letters pre and during the works. Further letters will be issued as necessary.

Task Odour abatement measures

in place.

Odorous

Contaminant

Level in

soil/water

Approx PPM

Potential for

Odour and or

VOC

Generation

without

measures

Potential for

Odour and or

VOC

Generation

with

measures

Breaking of

concrete

Initially perceived to remove all

concrete from 50% of site area.

On assessment it was decided

to break out only enough

concrete to allow for upcoming

excavation works to reduce

odour load.

10’s ppm Moderate

potential for

odour/voc

without

measures in

place.

Low with

measure in

place.

Water

treatment

plant.

off site

Fully abated air strippers for

removing volatiles.

10 to 100’s

ppm

High Potential

without

measures.

Very low

potential with

measures in

place.

Water

treatment

plant

Holding lagoons initially

installed at reduced levels to

reduce mobilisation of odours

by wind Lagoons later covered

100’s to

1000’s ppm

High potential

with initial

measures

Very low with

measure in

place.

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to reduce odour migration from

collected contaminated waters.

Covers added to silt separators.

Pumping of

contaminated

liquids from

excavations

Odours emanate from the fluids

stationary at the site surface

and in excavations. Pits or

trenches excavated to collect

the liquids with these being

pumped in sealed pipes to the

treatment system for immediate

treatment or contained storage.

Significant volumes not

identified on site, however

liquids are collected on a daily

basis from sumps to contain

and remove the potential odour

source. The footprint of

collection pits are minimised to

reduce surface area.

100’s to

1000’s ppm

Moderate

potential with

proposed

measures

Low to

Moderate

potential with

proposed

measures

Excavation of

concrete and

made ground

Concrete and made ground is

excavated and transported to

stockpile for crushing and

processing. Breaking and

excavation footprints reduced

as far as practicable.

0-10’s ppm Low potential

with proposed

measures

Low potential

with proposed

measures

Excavation of

deeper

materials

Soils to be excavated and

transported to processing areas

prior to treatment. A processing

area was set up at the in the

high bay warehouse area due

to its sheltered location.

Excavation areas will be

undertaken progressively with

dewatering undertaken ahead

10’s to 1000’s

ppm

Moderate to

Very High

potential but

very specific to

contamination

and

concentration.

Moderate to

High potential

but very

specific to

contamination

and

concentration.

May be

intermittent as

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of excavation to reduce odours

and improve handling of soils.

In addition working practices

will be altered continuously

including the temporary

covering of open faces whilst

excavation works ceased.

Footprints of the excavation are

reduced to maintain as small a

surface area as practical.

Excavation decisions based on

site observations, PID readings

and prevailing weather.

Targeted Odour suppressants

added at excavation as

discussed with the EA.

observations

are made and

reacted to.

Processing of

materials

The processing of materials to

be undertaken only when

absolutely necessary.

Equipment sited within the high

bay warehouse to reduce the

ability of wind to pick up and

transport odours where

possible. Material is moved

immediately from the

processing equipment to

treatment beds. Mobile odour

suppressant systems are sited

close to the processing areas.

Processing is undertaken in

controlled periods and with due

regard to prevailing conditions

to ensure that odour was kept

to a minimum. All beds

covered at present.

10’s to 100’s

ppm

Moderate to

high potential

but very

specific to

contamination

and

concentration.

Low to

moderate with

controls in

place.

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Treatment of

soils

Soils are prepared into

windrows for both drying (for

biological and geotechnical

purposes) and treatment. The

majority of soils are clays

requiring drying before

processing. By this stage the

odour level will have reduced

significantly with concentrations

up to 10 times lower following

excavation and processing. The

windrows are then turned

approximately fortnightly to

aerate the soils and promote

biodegradation.

Odour masking agents are

deployed to the site boundary

and mobile systems operate

adjacent to beds to assist in the

neutralising the odour. Odours

treatment windrows are

covered and recovered post

turning to reduce odour

generation from this material.

1 to 10’s ppm Moderate to

high potential

without control

but can be very

high for certain

contamination

and

circumstances

Moderate with

controls in

place.

Replacement

of treated

material

Materials are replaced as

targets are met based upon

previously agreed risk

assessments.

0 to 1’s ppm Low potential Low potential

The above measures are all be deployed to the site to control odour as far as is practicable with

a continuing re-assessment and review procedure in place.. It can be seen from the indication

of contaminant levels (concentrations in soil ppm from lab analysis) and from observations that

the phase of work most likely to produce odours is excavation with treatment bed turning being

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second and recovery of liquids following that. These activities will be undertaken in intermittent

phases and be complete by mid summer 2011. It is also clearly essential to note that while the

excavation phase is the most likely to contribute to odour, this site could not have been treated

in the comprehensive manner required unless the contaminated material is excavated and this

forms an important part of the overall treatment process and the strategy for the remediation of

the site..

In the Remediation method statement it was stated that the type of treatment for the

contaminated materials would be dependant of the types of materials excavated, with granular

materials being suitable for covered vapour extraction systems. The most appropriate and

practical treatment for the majority of the contaminated materials excavated, predominantly

dense compacted clays is to use uncovered mechanical bucket turned beds to assist with drying

of material and the breaking up of the clay to enable sustainable re-use of material.

The potentially most significant odour causing activities excavation and turning are discussed

further in the following sections.

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6.0 Mitigation Measures for Excavation Phases

As identified in the preceding, the excavation phases of the remediation project has the potential

to be the major contributor of site odours due to the excavation of the contaminated soils that

have been within the ground for potentially up to 70 years. The odours generated from the

excavation are increased commonly by the nature of the contaminants present and sometimes

by the concentrations that they occur in. For example, there are areas with very low

concentrations of chlorinated phenol type contamination which has a significant associated

odour due to its relatively low odour threshold however, it carries a very low potential for VOC

release due to its relatively low volatility. Conversely there are relatively high concentrations of

chlorinated solvents such as Tetrachloroethene (PCE) which have relatively low odours

compared with the concentration but a greater potential for VOC release.

We continually refine the design of all contaminated site remediation in response to what we find

on site and to surrounding environmental conditions. The processes, procedures and working

practices will continue to be developed on a constant programme if benefit can be realised from

the amended practice. This is essential good practice on all contaminated land remediation

projects and is something our site management team constantly review. Any amendment is

generally discussed and agreed with the EA officer enforcing our licence unless immediate

effect can be released from its implementation in which case benefits are discussed following

implementation. In this case these amendments will also be discussed with the Contaminated

Land team at SCDC to ensure we continue with the open policy we have maintained with the

regulators to date.

It is important to note that the site did have a background odour and VOC footprint before works

commenced as does the area around the site which is also contributed to by local traffic.

The following specific measures are those which we have implemented either as initially

planned or have implemented in response to site or environmental conditions.

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We will not undertake excavation, processing or hauling of contaminated soils during

evenings, weekends or Bank Holidays (working hours 08:00 – 18:00) to ensure that at

sensitive times the risk of odours is at a minimum.

We will continue to monitor the weather (via our on site weather station) and site

conditions closely and take due regard. Specifically on days where conditions are likely

to or indeed do show evidence that odours may be transmitted off site, working areas will

be adapted, where possible, to reduce odour impacts off site as far as reasonably

practicable. It must be noted that simply temporarily ceasing excavations on site will

lengthen the programme of works, creating a longer period of time for the potential of

odour release and ceasing works will not remove or reduce the potential for odour

generation in the future. The proposed adaptive method is most the most suitable

approach.

We undertake two daily patrols as part of our monitoring regime of odours and

concentrations off site. We will continue this and report them to the regulators as

required.

We will maintain and operate the odour suppressant system around the perimeter of the

site 24 hours a day, 7 days a week..

The excavation will be lead by an Environmental Engineer who will monitor VOC and

odour emission at the excavation face. He or she will advise the excavation team on

how this material should be handled to best control its odour emission. He or she will

liaise on a regular basis with the Engineers recording weather conditions and monitoring

odour and VOC emissions around the site boundary to ensure the excavation is

controlled as far as reasonably practicable.

The speed that contaminated material can be handled with regards to the management

of odour has been identified, only one excavator will be used to excavate the odorous

contaminated soils from the main dig. Only under appropriate weather or site conditions

will two or more excavators be permitted to excavate odours soils.

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The daily volume of contaminated soils excavated will be limited to a volume that is

capable of being processed and covered in the same day. Odours materials will not be

left in a stockpile overnight, the volume of freshly excavated contaminated material must

be of a suitable volume that it can be covered at short notice to manage odours.

Continuously highly odours soils excavated may be left in the excavation at depth in an

area away from the receptors to allow the odours to dissipate, before hauling the

materials to the treatment area.

In order to react to any changes in weather condition it is integral to have an emergency

mitigation measure cover system on standby, along with an appropriate level of staff to

operate them effectively.

We will install and operate mobile masking and neutralising systems focused solely on

the freshly excavated materials to help concentrate abatement efforts at the source of

the odours. This system will as closely as practicable follow the excavating plant around

the working area, to ensure that each bucket of freshly excavated soils is doused to

reduce odour generation. The proprietary mixture used attempts to neutralise and mask

odours in much the same way as household fresheners work. Note that not all

excavated materials will release odours upon excavation.

At the end of the working day the excavation face will be sealed in with the back of the

machine bucket to prevent odour generation overnight. An olfactory assessment will be

conducted by the one of the Environmental Engineers at the excavation face, if

significant odours are detected after sealing the excavation face, temporary covers will

be placed on the excavation to reduce odour generation further. Temporary cover

systems will be utilised to reduce odour generation at anytime they are required, in

particular at the weekend.

Non-working, odourous excavation faces will be covered.

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7.0 Mitigation Measures for Turning windrows

The activities and conditions following excavation are significantly different from those

encountered during the excavation phase. We do not expect odours to represent in such a

concentrated manner for turning operations as for excavations.

The following specific measures are for use at the site for this phase of work which we believe

will mitigate the odours as far as practicable given our current understanding of the site and its

contaminants. This may be further reviewed as treatments progress ad conditions change.

Subsequent paragraphs explain the actions we will propose to take should conditions change

particularly as the season develops and weather conditions change.

We will not undertake turning of soils or excavation of beds during evenings, weekends

or Bank Holidays (working hours 08:00 – 18:00) to ensure that at sensitive times the risk

of odours is at a minimum.

We will continue to monitor the weather (via our on site weather station) and site

conditions closely and take due regard. Specifically on days where conditions are likely

to or show evidence that odours may be transmitted off site working areas will be

adapted appropriately turning beds which represent off site working areas will be

adapted appropriately turning beds which represent lower risks of odour or in more

appropriate positions on site for example.

We will maintain and operate mobile masking and neutralising systems to help

concentrate abatement efforts on the beds we are turning. The proprietary mixture used

attempts to neutralise and mask odours in much the same way as household fresheners

work. The systems will be placed next to the bed and the agent deployed to the soil as

closely to the turner as is safe to do so during the turning of the windrows unless agreed

otherwise with the regulators. Note that not all beds being turned require odour control

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measures, as it is likely that materials nearing the end of the treatment process contain

very low levels of contaminants and little or no detectable odour.

Any odorous treatment beds that have been uncovered and subjected to treatment and

processing must be covered at the end of the day in order to control odour generation.

All odorous materials must be covered at all times during the treatment phase with the

exception of construction and turning.

Should we need to store any treated materials on site for extended periods post

treatment due to operational restrictions, we will reduce the footprint (i.e. reduce the

potential surface area for odour release) and seal the surface of the stockpile where

required to reduce the potential for background odour from this material.

As we need to turn odorous beds along any boundary they will only be turned when the

wind direction and speed will allow for any odour dilution across the site, not directly over

the boundary thus reducing the impact on residents in both Hauxton and Harston.

All odorous treatment beds will be covered when not being turned to prevent the odour

from this material being released uncontrollably. Covering of treatment beds will clearly

only be effective should the odour be emanating from the static beds. However, this

covering will have a detrimental and prolonging effect on the treatment process and will

undoubtedly increase the complexity of the operation. As contaminant levels reduced in

the windrows as a result of the treatment process, so does the potential to generate

odours. Therefore material with low levels of contaminants may not generate odours thus

not require covering and will significantly benefit from being exposed to allow drying of

the materials.

Treatment beds in general require to be turned fortnightly to increase air flow through the

material, promoting biodegradation of the contaminants within. Turning the beds with

mechanical buckets has the potential to generate odours, therefore a weekly turning

schedule will be designed, and reviewed on a daily basis. The turning schedules main

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function is to ensure certain treatment beds are turned under favourable weather

conditions, therefore reducing the migration of site odours towards residential areas.

Weather forecasts for the coming week, recent treatment bed analysis and olfactory

assessment of treatment beds will be used to make onsite decisions on what treatment

beds can be turned without generating site odours from the process to migrate off site

towards potential receptors.

Outline Turning Protocol

Odour

profile

level

Environmental Conditions to

permit turning treatment bed

compulsory

control

measures

Monitoring.

LOW All environmental conditions

Maintain

perimeter

odour control

system

Maintain general level

of monitoring

MEDIUM

Favourable environmental

conditions that suggest good

dispersion. Consider not turning in

extremely still or exceptionally hot

conditions. Ensure beds of this

category near to boundary of site

receive suitable dispersion across

site.

All above and

ensure mobile

systems are

available close

at hand if

required.

Ensure that personnel

make regular off site

observations and PID

readings to supplement

base level monitoring.

HIGH

Only to be turned under perfect

environmental conditions for

dispersion. Lower temperature,

good air movement and little

prospect for temporary changes in

conditions.

All above and

ensure all

mobile

systems are

focused on the

bed and are

fully

Ensure previous levels

of monitoring and

consider stationing a

member of personnel

off site for extended

periods in direction of

wind to monitor for

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operational for

duration of

turning.

odours.

VERY

HIGH

Only to be turned under perfect

environmental conditions for

dispersion. Lower temperature,

good air movement and little

prospect for temporary changes in

conditions.

All above and

ensure all

mobile

systems are

focused on the

bed and are

fully

operational for

duration of

turning.

Ensure previous levels

of monitoring and

consider stationing a

member of personnel

off site for extended

periods in direction of

wind to monitor for

odours.

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8.0 Summary

In summary we would propose the following way is the most appropriate to proceed in order to

ensure that the project continues to move forward whilst continuing to be as protective to both

human health and local comfort as possible.

Continue the measures as described in this document.

Meet on site with the SCDC and the EA regularly and establish an odour profile around

the site and surroundings at rest.

Continue turning windrows having due regard to environmental conditions.

Continually liaise and review procedures.